Pat the chicken breast dry with a paper towel and cut into bite-sized 1-inch cubes.
Season the chicken evenly with sea salt and black pepper.
In a small bowl, whisk together the tamari, toasted sesame oil, rice vinegar, honey, minced garlic, and grated ginger to create the stir-fry sauce.
Heat the avocado oil in a large skillet or wok over medium-high heat until shimmering.
Add the chicken to the pan in a single layer and sear for 3-4 minutes until golden brown and cooked through.
Remove the chicken from the pan and set aside on a plate.
Add the broccoli florets to the same pan with a splash of water, cover with a lid, and steam for 2 minutes until bright green and tender-crisp.
Return the chicken to the pan and pour the garlic-ginger sauce over the mixture.
Toss everything together for 1-2 minutes until the sauce thickens slightly and coats the chicken and broccoli.
Serve the stir-fry immediately over the warm cooked brown rice.